1. Field of the Invention
The present invention relates to perforated sheet material and a dispensing system for dispensing the sheet material. More particularly, the present invention relates to perforated sheet material and a dispensing system for dispensing individual segments of the sheet material from a dispenser.
2. Description of Related Art
A number of different types of sheet materials can be dispensed from a source. Typically, these materials are wound into a roll either with or without a core to provide a maximum amount of material in a relatively small amount of space. Some examples of these materials include paper towels, tissue, wrapping paper, aluminum foil, wax paper, plastic wrap, and the like.
For example, paper towels are either perforated or are not perforated. Non-perforated paper towels are typically dispensed from dispensers by rotating a crank or moving a lever each time the user desires to remove material from the dispenser. Although these types of dispensers are effective at dispensing individual segments from sheets of material, a user must make physical contact with the crank or lever each time the user desires to dispense the sheet material from the dispenser. For example, during a single day in an extremely busy washroom, hundreds or even thousands of users may physically contact a dispenser to dispense paper toweling therefrom. This leads to possible transfer of germs and a host of other health concerns associated with the spread of various contaminants from one user to another.
Attempts have been made to limit the amount of user contact with a dispenser. For example, U.S. Pat. No. 5,630,526 to Moody, U.S patent application Ser. No. 08/851,937, filed on May 6, 1997 now U.S. Pat. No. 5,868,275, and U.S. Pat. No. 5,335,811 to Morand, the entire disclosures of which are incorporated herein by reference, disclose systems for dispensing individual segments of sheet material from a roll of sheet material having perforated tear lines separating the individual segments. Pulling an end-most segment of the sheet material tears the end-most segment away from the remaining material along a perforated tear line separating the end-most segment from the remainder of the material. Dispensing systems of this type are known as "touch-less" because normally the user is not required to touch any portion of the dispenser itself. During dispensing, the user grasps only an end portion of the sheet material with one hand or both hands and pulls the sheet material from the dispenser.
With these touch-less types of dispensing systems, on any given attempt the result may fail to meet some of the desired criteria, and thus, cause some level of dissatisfaction. For example, a sheet may fail to separate fully along the first perforation tear line resulting in the dispensing of multiple sheets. In addition, the remaining sheet material end portion may not extend a sufficient distance from the dispenser outlet, requiring a user to subsequently dispense sheet material while touching the dispenser and thereby defeating its purpose. Alternatively, the remaining end portion may extend so far as to be unsightly and more susceptible to soiling. Lastly, the user may obtain substantially less than a full sheet of material when the tensioning forces applied by the dispenser in order to initiate separation along the perforation tear lines are greater than the strength of the material at the user/material interface. This last type of failure is known as tabbing.
Tabbing occurs more frequently when the sheet material is an absorbent material, such as a paper towel, and when the user grasps this absorbent material with one or more wet hands. Typically, the wet strength of such materials is less than 50% of the dry strength, and, more typically, is 15% to 30% of the dry strength. Thus, when the sum of the tensioning forces exerted on a sheet of absorbent material by a user with wet hands exceeds the wet strength of the material, tabbing is likely to occur. Further, the strength of most sheet materials, wet or dry, is not typically equal in all directions, but typically weaker in the cross machine direction, where machine direction refers to the manufacturing process orientation in the plane of the web and cross machine direction is orthogonal in the plane of the web to the process orientation.
Thus, it is desired to improve reliability of dispensing such that the user obtains a single, fully intact sheet which has separated cleanly and completely from the remaining material along the perforated tear line and where a sufficient length, typically about 2 to 4 inches, of the remaining end portion of sheet material extends from the outlet of the dispenser so as to be available for subsequent dispensing.
In light of the foregoing, there is a need in the art for improved sheet material and an improved dispensing system which increases reliability of single sheet dispensing of sheet material.